1. Field of the Invention
An aspect of the present invention relates to a liquid crystal display device and a driving method thereof, and more particularly, to a liquid crystal display device and a driving method thereof, which can reduce power consumption and improve quality of images displayed.
2. Description of the Related Art
With the development of information technologies, the importance of display devices has come into the spotlight as connection media between users and information. Accordingly, the use of flat panel display devices (FPDs) is increased, such as liquid crystal display devices (LCDs), organic light emitting display devices (OLEDs) and plasma display panels (PDPs).
Among these FPDs, the LCDs can implement high resolution and have not only a smaller size but also a larger size. Thus, the LCDs are widely used.
An LCD displays an image using electro-optical characteristics of liquid crystals. To this end, the LCD may include a color filter substrate and a thin film transistor (TFT) substrate, which are disposed opposite to each other with the liquid crystals interposed therebetween.
The color filter substrate implements colors of an image displayed through the LCD. To this end, the color filter substrate may include a black matrix and a color filter.
The TFT substrate applies the voltage of a data signal for driving the liquid crystals. To this end, the TFT substrate may include gate lines, data lines, TFTs and pixel electrodes. The TFT substrate may further include a common electrode. Here, the common electrode may be formed on the color filter substrate, corresponding to a liquid crystal driving method.
The LCD described above supplies the voltage of a data signal to the pixel electrode using the TFT included in each pixel. In this case, the liquid crystals are driven by the difference in voltage between the pixel and common electrodes, thereby displaying a predetermined image. Meanwhile, in a case where DC voltage having the same polarity is applied to the liquid crystals for a long period of time, deterioration of the liquid crystal occurs.
In order to prevent the deterioration of the liquid crystals, there is used a polarity inversion driving method in which the voltage of a data signal applied to the liquid crystals is periodically changed. The polarity inversion driving method is divided into a frame inversion driving method, a line inversion driving method, a column inversion driving method, a dot inversion driving method, etc.
Among these inversion driving methods, in the dot inversion driving method, a data signal having a polarity opposite to that of all pixels horizontally and vertically adjacent to each pixel is supplied to the pixel, and the polarity of the data signal is inverted in every frame. In the dot inversion driving method, flickers occurring between vertically and horizontally adjacent pixels are offset to each other. Thus, the dot inversion driving method provides images with image quality superior to the other inversion driving methods.
Meanwhile, in a case where polarity of a data signal is periodically changed, the voltage of a gate signal is determined in consideration of both positive and negative data signals. In other words, a gate-on voltage Von is set so that the TFT can be turned on by the voltage of the positive (+) data signal, and a gate-off voltage Voff is set so that the TFT can be turned off by the voltage of the negative (−) data signal.
In this case, the gate-off voltage Voff significantly lower than that of the positive (+) data signal is applied, and the gate-on voltage Von significantly higher than that of the negative (−) data signal is applied. Therefore, power consumption is increased.
In a case where the voltage difference between the gate-on voltage Von and the gate-off voltage Voff is large, a kick-back voltage is generated, and therefore, the image quality is degraded.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.